1. Field of the Invention
The present invention relates to a method for producing a support element, a housing lid or for insertion into a housing lid, having an angle sensor for sensing the angle of rotation of a shaft rotating in a housing an electrical plug-in connections, wherein the support element comprises plastic, e.g. thermoset or thermoplastic, and electrical components are overmolded or recast with a plastic. The subject matter of the present invention is also a support element having an angle sensor for an actuator in an internal combustion engine, wherein the angle sensor comprises a magnet, associated with the actuator, and electronic components equipped with electrical plug-in connections, such as a consumer plug.
2. Prior Art
Support elements with an integrated angle sensor are used in internal combustion engines, to sense the rotary position of actuators for controlling the internal combustion engine, for example for load control, exhaust return, air flaps in the intake section or the adjustment of the blades in a turbocharger. The design as a housing lid has the advantage that the angle sensor itself is sealed in a physical unit to be protected, the electrical connections are in the form of consumer plugs configured according to customer requirements for electrical connection to the engine electronics.
The actual angle sensor usually comprises at least one magnetoresistive measurement pickup or Hall sensor, typically a semiconductor wherein the measurement pickup has a respective associated chip with evaluation electronics. Frequently, the angle sensor also comprises capacitors in order to improve electromagnetic compatibility. An advantage is the redundant design with two measurement pickups and two associated evaluation electronic units in order to increase security when sensing the rotation angle position of a throttle valve (E-gas), for example.
The production of housing lids, with an integrated angle sensor has been such that the measurement pickup and the evaluation electronics unit are preconfigured by a chip manufacturer, i.e. the chip for the evaluation electronics unit and the measurement pickup are electrically connected, for example by bonding, to a stamped grid for the purpose of making external contact, and then the electronic components are individually overmolded with a thermoset. A check is then performed by the manufacturer, and the preconfigured angle sensor is then supplied to a customer. The latter obtains a housing lid blank comprising plastic, which is usually produced by means of injection molding, from a further manufacturer and produces the angle sensor module by first of all electrically connecting the preconfigured angle sensor to what is known as a leadframe by welding or soldering. Next, the leadframe is inserted into the housing blank, and the leadframe is overmolded with a thermoplastic, a separate cover needing to protect the sensor system, since it would otherwise be damaged. Finally, it is again necessary to perform an operational check on the finished housing lid.
In summary, the production method to date can be characterized by three injection-molding operations, with both the partial overmolding of the stamped grid by the chip manufacturer and the final overmolding of the leadframe for connection to the housing lid needing to take place under particular process conditions in order to avoid the risk of operational faults. Finally, two operational checks are also required, namely by the chip manufacturer following production of the sensor and by the manufacturer of the support element following overmolding of the leadframe.
The definition of the actual angle sensor on the support element by overmolding also inevitably results in the measurement pickup being separate from the rotary magnet to be sensed by virtue of at least two plastic walls or layers. The resultant greater interval impairs measurement accuracy and requires stronger magnets.
DE 196 18 631 A1 discloses the practice of filling a housing of a measuring apparatus completely with casting compound after the electrical components have been arranged. DE 4 115 883 A1 describes the production of a casting with embedded electrodes, and EP 1 275 939 A2 describes an angle sensor seated on a printed circuit board.